PROJECT SUMMARY Bioactive sphingolipids constitute a family of related molecules with profound effects on key cancer attributes. This proposal focuses specifically on heretofore unappreciated roles for an acid sphingomyelinase (ASM)/ceramide kinase (CERK)-mediated pathway of sphingolipid metabolism in regulating the formation of tumor cytokines and chemokines with roles in tumor inflammation and invasion. Our recent published studies demonstrate that ASM-generated ceramide is coupled to the action of CERK, resulting in the formation of ceramide 1-phosphate (C1P) with a key role in mediating the specific production of chemokines (e.g. CCL5) and cytokines (e.g. IL6) in response to TNF and IL1. Additional studies also disclose a key role for ASM and CERK in regulating tumor cell invasion and metastasis. These results, coupled with the increased appreciation of roles of TNF, IL1, CCL5 and IL6 in cancer inflammation and metastasis, have led us to the hypothesis that this novel ASM/CERK/C1P pathway defines a previously unappreciated mechanism regulating invasiveness and metastasis of breast cancer, with potentially important roles in cancer metastasis. We will evaluate this hypothesis by pursuing the following specific aims: 1.To define the roles and mechanisms by which the ASM/CERK/C1P pathway regulates the production of inflammatory mediators. 2. To establish the role of CERK in cancer growth and metastasis. 3. To advance CERK as a novel therapeutic target for breast cancer by solving its structure. Taken together, these studies are key in not only defining novel pathways and mechanisms of sphingolipid-mediated cancer biology at a molecular and cellular level, but also for charting novel therapeutic potentials. The studies proposed in this project aim at defining how an enzyme of lipid (fat) metabolism regulates some key functions of cancer cells that result in the production of factors that regulate the ability of the tumor cells to migrate and invade which are critical for cancer metastasis. Understanding these novel pathways and mechanisms not only enhances our understanding of cancer behavior, but also promises to lead us to the identification of novel targets for developing new inhibitors of cancer metastasis.